fix: resolve TypeScript compilation errors after rebase

- Remove unused tauriOpen import in ClaudeCodeSession
- Replace invoke() with apiCall() in api.ts for web compatibility
- Fix unused variable warnings

These changes ensure the frontend builds correctly with the new
web server mode while maintaining compatibility with Tauri desktop mode.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>